I-MR-R Chart in Excel using QI Macros

The I-MR-R chart is a combination of XbarR and XmR Chart. It gives both "within" group and "between" group variation, It:

  • Calculates the average of subgroups, just like an XbarR
  • Creates the Range chart (within group variation) just like the XbarR
  • Creates a Moving Range Chart (between group variation) like an XmR using the average of the subgroups.
  • Creates the Individuals Chart like an XmR using the average of the subgroups.

Analyze Variation with a I-MR-R Control Chart

 

How to Create an I-MR-R Chart:

  1. Select two or more columns of data.
  2. Click on the QI Macros pull-down or ribbon menu, select Control Charts then "I-MR-R chart".
  3. Enter titles for your charts when prompted:
    • X or Individuals chart
    • MR - Moving Range
    • R - Range
  4. Analyze and interpret the results:
    • Evaluate the range charts first. If they are "out of control," so is the process. If the range charts look okay, then evaluate the X chart.
    • Unstable points or trends will turn red and need to be investigated. I-MR-R/S Chart in Excel using QI Macros

You can also create the chart using prior versions of the QI Macros XbarR and XmR Charts:

Here's how to do it with the QI Macros:

  1. Run an XbarR Chart on your data to get the R Chart (or XbarS chart if you want the S Chart).
  2. Select the averages calculated for this chart (hiding behind the Xbar and R Charts) and run an XmR (I-MR) chart on the averages.
  3. Copy the R chart from the XbarR chart to the XmR charts and you'll have an I-MR-R chart.

Example using XbarR Test data:

  1. Run an XbarR Chart on your data (two or more samples) to get the R Chart 
    (or run an XbarS chart if you want the S Chart):

    XbarR Chart in Excel using QI Macros

  2. Select the averages calculated for this chart (hiding behind the Xbar and R Charts) and run an XmR (I-MR) chart on the averages.

    I-MR  Chart in Excel using QI Macros

  3. Copy the R chart from the XbarR chart (or S Chart from XbarS Chart) to the XmR charts and you'll have an I-MR-R/S chart.

    I-MR-R/S Chart in Excel using QI Macros

This gives the following:

  • An Individuals chart of the subgroup means
  • A moving range chart of the subgroup means (Between)
  • A range chart of the subgroups (Within)

It takes two steps in older versions, but produces the desired charts.

To create an I Mr R S Chart using QI Macros...
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